// Timetable group list page renderer.

const { renderView } = require('../../../view');
const { normalizeTimeZone } = require('#src/data/timetables');

function formatDateInTimeZone(value, timeZone) {
  if (!value) {
    return '';
  }

  const date = new Date(value);
  if (Number.isNaN(date.getTime())) {
    return '';
  }

  const resolvedTimeZone = normalizeTimeZone(timeZone, 'Europe/London');
  return new Intl.DateTimeFormat('en-US', {
    timeZone: resolvedTimeZone,
    month: 'short',
    day: '2-digit',
    year: 'numeric',
    hour: 'numeric',
    minute: '2-digit',
    second: '2-digit'
  }).format(date);
}

function formatNextStartLabel(value, timeZone) {
  if (!value) {
    return 'No entries';
  }

  const label = formatDateInTimeZone(value, timeZone) || String(value);
  return label || 'No entries';
}

module.exports = function renderTimetableGroupsPage(data, message, currentUser) {
  const timetableGroups = (data.timetableGroups || []).map(function (timetableGroup) {
    const timeZone = normalizeTimeZone(timetableGroup.timezone, 'Europe/London');
    return Object.assign({}, timetableGroup, {
      timeZone: timeZone,
      nextStartLabel: formatNextStartLabel(timetableGroup.next_start_datetime, timeZone),
      nextStartValue: timetableGroup.next_start_datetime ? new Date(timetableGroup.next_start_datetime).toISOString() : ''
    });
  });

  return renderView('data-sources/timetables/list', {
    title: 'Timetables',
    active: 'timetables',
    message: message,
    currentUser: currentUser || null,
    timetableGroups: timetableGroups,
    pagination: data.pagination || null
  });
};